Antitumor mechanisms of an exopolysaccharide from Lactobacillus fermentum on HT-29 cells and HT-29 tumor-bearing mice

We have obtained an exopolysaccharide (YL-11 EPS) produced by Lactobacillus fermentum YL-11 isolated from fermented milk and confirmed that it can effectively inhibit colon cancer HT-29 cells proliferation in vitro. The aim of this study is to study anti-colon cancer effect in vivo and its possible mechanisms. Animal assays indicated YL-11 EPS treatment significantly suppressed the growth of HT-29 tumor xenograft without exhibiting obvious negative effects on normal cells. Cell experiments demonstrated YL-11 EPS treatment up regulated the ratio of Bax/Bcl-2 and induced the decrease in mitochondrial membrane potential and improved the expression of cleaved caspases-3 and cleaved PARP proteins, and finally induced HT-29 cells apoptosis, suggesting the involvement of mitochondrial pathway. Moreover, YL-11 EPS can block the PI3K/AKT signaling pathway and arrest the cell cycle in G1-phase to exert its anti-colon cancer activity. Overall, YL-11 EPS can be explored as a potential nutraceutical to prevent colorectal cancer.